Yellow Xanax is a benzodiazepine drug, the trade name for Alprazolam. You can now easily buy Yellow Xanax Bars Online. Xanax helps treat Anxiety caused due to depression. Xanax works by enhancing the activity of GABA (a neurotransmitter) present in the brain. Yellow Xanax bars are yellow with 'R 0 3 9' imprinted on it. Xanax is used for treating anxiety disorders, panic disorders with or without agoraphobia, GAD (generalised anxiety disorder), chemotherapy-induced nausea, and other treatments. Alprazolam is for short-term management of Anxiety. It is taken orally, and the improvement in GAD can be seen within a week.